UN humanitarian chief urges protection of civilians in Mosul

A top humanitarian official at the UN has said he is "extremely concerned" for the safety of 1.5 million Mosul residents as Iraqi forces begin a long-awaited operation to liberate the city from Islamic State control.

Iraqi Prime Minister Haider al-Abadi announced late on Sunday the start of the offensive to retake Mosul, which fell into militants' hands in 2014.

While military operations have been planned for several months, humanitarian agencies have warned they could be overwhelmed by the mass exodus of residents escaping the fighting.

"Depending on the intensity and scope of the fighting, as many as one million people may be forced to flee their homes in a worst-case scenario," Under-Secretary General for Humanitarian Affairs and Emergency Relief Coordinator Stephen O'Brien said.

The Iraqi government dropped leaflets over Mosul just hours before launching its US-backed offensive, warning residents to stay in their homes.

However many are at "extreme risk" of being caught in cross fire or targeted by snipers, O'Brien said, if they attempted to reach safety.

"Tens of thousands of Iraqi girls, boys, women and men may be under siege or held as human shields," he added.

"Thousands may be forcibly expelled or trapped between the fighting lines."

He urged that civilians were protected from the fighting, adding: "Nothing is more important."

Shelter is available for 60,000 people in camps and emergency sites, while construction of additional camps to receive 250,000 more people is under way.

Food rations for 220,000 families are ready for distribution, 143,000 sets of emergency household items are in stock; latrines and showers are being readied for dispatch and 240 tonnes of medication are available at distribution points, O'Brien added.

"Despite generous contributions from donor countries, funding has been insufficient to prepare fully for the worst-case scenario," he said.

"With the resources available, humanitarian partners have done their best to prepare as efficiently as possible. Working under some of the most difficult and insecure conditions in the world, humanitarian partners will be doing everything possible to help as many people as possible in the days and weeks ahead."